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1974 R90/6 refurb

I'm calling this a refurb, not a restore, since I'm not trying to make it a showpiece, but rather a reliable and fun bike to ride. My first bike was an R75/5 LWB that I bought when I became a "man" at 18. I bought it from a buddy who got an R90/6. We had great times back then.

Here's a quick picture I shot once I got the bike home. It ran OK, missed a bit here and there, but seemingly sound. I paid $3200 for it.:
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And now on the lift with the fairing removed. I plan to keep the bike naked. I love my RT, and so I don't need another and I want a naked bike.
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The carbs were not working well, so I took them off for a rebuild. Here's one in pieces, waiting for the Bing kit arriving Friday.
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One thing I learned is that you can't trust anything is working properly on an old bike. I noticed the choke was rough, and since I had some time waiting on parts, I decided to take it apart. You can see the ball bearing, that is supposed to be riding in the little hole with the spring, is actually jammed into a slot. I pried it out, cleaned up and greased the mechanism, and put it back together. Man, it works so smoothly now, it was worth the time.
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Here is the assembly back together. The ball bearing falls into a detent and it operates smoothly and clicks right into place. I just need some carbs to connect to it!
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The gauges weren't lighting up and working properly, so apart they came. I found broken tabs for one of the lights. Here's a picture of a good copper tab that is the contact for a light bulb.
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The problem was that two of the tabs were missing for one light. I soldered on wire and bent it over at 90 degrees to make a new "tab" out of wire. It works!
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Gauges back together:
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I also ordered and just installed new throttle cables. The ones I had were stiff and rotted. I tried to lube them, but they were too far gone. The new ones are really smooth. Again, waiting for carbs!

I drained the fork oil and it was brown and nasty, like old beer. And a lot of particulate gunk came out. The forks were squeaky and sticky. I ran about 100 mls of fork oil through them to flush them out somewhat, and then filled with fresh oil. They are quiet and operate nicely now.

The tank had some rust in it, so I soaked it in Navel Jelly and water over night, then washed it well with water. This cleans up a tank pretty well. The POR treatment is too costly, I'll just use inline filters in case any rust is left.

New spark plug wires should be here soon, too. Then, with rebuilt carbs, plug wires, and the tune up done, I hope to have it running well this weekend.

Had a good day in the shop. I got the Bing kits and assembled the carbs. Today, it fired right up w/o adjustment. I took it out for a ride to get it warm, then fine tuned the Bings and she idles well.

There's a noise at idle up front, on the front end by the cam shaft (where the points are), that I can't tell if it is normal valve train noise or a problem. If it is a problem, I'll know soon enough cause I'm not messing with it until it becomes obvious.

The throttle is very nice now. Comes on smooth and snaps closed fast. No missing from a take off, and even cold, it fires up instantly. New throttle cables were a must.

I serviced the handle bar switches. They were working intermittently. The contacts were corroded and one had a spider nest in it. Cleaned, lubed, and working great now.

One setback is that the headlight bucket was apparently cut short for the fairing and won't accept a headlight and beauty ring. I ordered a new bucket on ebay for $55 shipped and that should work fine. It'll be a bit of work to install it, but that will force me to look at all the wiring in there and perhaps get into the steering head bearings.

Everything I look at needs some type of service.

Here's a cool trick I learned on the web (from one of the many sites recommended by you guys) for installing O-rings over a threaded shaft, such as this choke assy:
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Just put some tape over the threads, then slide on the O-ring with a little silicone grease:
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Here's two pictures showing the cut light bucket. You can see it has been cut back so that it is short, and, no longer round to accept a headlight:

Valve covers?

WOW good work - that headlight bucket being cut back is a real pisser

I removed my fairing on 74 R75/6 and was able to install headlight with no other work boy was I a happy camper!!

OK questions on Valve covers my 74 has the peanut type valve covers looks like yours has a newer valve cover installed. Any other opinions on this or were the
1974 R90's the first to have these valve covers??

OK questions on Valve covers my 74 has the peanut type valve covers looks like yours has a newer valve cover installed. Any other opinions on this or were the 1974 R90's the first to have these valve covers??

The "new" valve covers should have come out with the '77 /7 models. Not all were the black coated like this...but the squarish shape started then.

Yep, the bucket being cut was a bummer. The cost of a new one was not bad, but it was a lot of work to swap it out. And I see no reason for it to have been cut in the first place!

Now that I have the light on with the new bucket, and I synched and tuned the carbs, I decided to take the bike out this dark evening. It was a cold engine, but it fired right up and idled well. I let it idle for about a minute, then backed off the choke and took off. I rode about 10 miles, and it ran perfectly, no miss, the entire time. So that's it, it is nice.

Now I have it where I want. Running well and looking OK. I can tackle the last items at my leisure. Those are:

I'm sure more will pop up, but each of those makes a good, independent quick project so I can ride, work, ride. And she's riding nicely.

The transmission shifts up fine, but is a bit hard to get from 3d to 2d. I have to keep hitting the shifter to get it to go, so something is not right there. If anyone has any thoughts, I'm listening!

Here I am in the process of installing the new light bucket. I had an extra circuit board so I carefully removed one wire at a time, placing it on the new board. Then I swapped the bucket, and put each wire back on the original board. With breaks, repairs, etc., it took about 4 hours.
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Here it is complete. There was no plug for the new headlight, so I bought a generic one at the auto store and soldered on female spade connectors to plug it in to the circuit board. Only set me back about $4.
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Back together, light in place:
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And from the side.
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Once I complete the last items, I'll put a plate on it and take it on a more proper ride.

The transmission shifts up fine, but is a bit hard to get from 3d to 2d. I have to keep hitting the shifter to get it to go, so something is not right there. If anyone has any thoughts, I'm listening!

This could happen if the transmission input spline shaft has old lube or no lube on it. Try cleaning up the spline shaft and lubing it with the right stuff. Also, what gear oil are you using? There have been some recommendations on here that should help alleviate shifting problems

If that non-drilled rotor is in good shape you should take it off and offer it up to someone who is doing a restoration. An EBC brake rotor with the right pads will improve your braking, the non-drilled rotor is hard to find for those that want them.
$0.02
That 'comfort seat' that you have is the best of the cowl seats. All said, This is looking pretty nice. Keep it up!

I am glad to hear that a spline lube might fix it. Judging by the crappy brown beer I drained from the forks, the congealed grease everywhere, and the grease like crud in the front brake caliper, I'd say the splines are likely to need a lube!

The front disc had wear, but it does work and certainly would work for a restoration if you were trying to go original. It wouldn't hurt to resurface it if it has enough thickness.

If someone needs/wants it, PM me. I wouldn't think it would be more than $10 to ship and I don't want anything for it.

History on bike?

It is interesting, obviously with aluminum rear turn signals, kickstart transmission and bings it looks like a 1974. Tank, seat, rear cowling, rocker covers are from later model. Hope you can find some aluminum front turn signals, I had to replace mine on a 1975 and when I got them they were black plastic. I have heard lots of people say steer clear of a 1974 but I absolutely love mine. Had to put a lot of money in it (wife named it the Black Hole) but it is an absolute joy to ride now. I kind of messed it up by putting in an electronic ignition which didn't last 10k, now running on points again and runs better and smoother than ever.

Yeah, over the years, before I bought it, it has become a blend of years. But that's OK. I put some old turn signals on that I had. They look good, but add to the Frankenstein nature. It's just that the aluminum ones are expensive used, and I'm not going to spend that now on the bike---"black hole."

I guess the problem with 1974 is the transmissions. I guess they had issues and many parts are not available. If it fails, the option of buying a used one and doing a rebuild is there. Hopefully I won't have to make this decision.